1. Field of the Invention
This invention relates in general to electrooptical distance measurement apparatus, such as may be used in field and land surveying. More in particular, the measurement may be facilitated, where visual contact between the end points of the distance is impaired or obstructed, e.g. by a forest, house, mountain, etc., or where one of such end points is not accessible.
2. Description of the Prior Art
The well known electrooptical measurement of distances between points may be difficult if such points have a limited accessibility. If a point is part of a wall or house corner, the optical reflector, due to its shape, may not be placed at or above the point. Furthermore visual contact over the distance may be impossible. In the first case it is known to place certain points of the reflector housing, provided for this method, at the point to be measured. (See instructions for use of "Electrooptical distance measurement device Kern DM 501" available from Kern & Co. AG, CH-5001 Aarau, Switzerland). Known sighting devices inserted into the tilting axis of the reflector case may also be supported on such point and at the same time used to aim the reflector on the master station at the other end of the distance. Thus the reflector is set up with a known eccentricity extending parallel or at a right angle to the distance, which has to be taken into account.
In case of no visual contact over the distance it is known to find, by means of a right angle sighting device, a point with visual contact to both ends of the distance, where the directions to said end points form a right angle. The reflector is then placed at this auxiliary point to measure the distances to the end points, and the distance is calculated from the measured distances. These known methods imply an appreciable amount of work and apparatus.
An object of the present invention is, therefore, to provide a reflector for electrooptical measurement of the distance between points, which may be set up in a simple way and without accessories at an auxiliary point at a given angle and near to the distance and facing one of the points.
The foregoing object, other objects as well as the numerous advantages of the present invention are set forth in the following disclosure.